Vivi Tsalmantza and I attempted to re-start our project looking for double-redshifts in the SDSS spectroscopy. We discussed the issues of wavelength coverage—which, with empirical galaxy templates, is a function of the two redshifts—and interpolation, which ought to be done by cubic spline (with SDSS spectra, at least). I started writing up the issue of hypothesis testing in this situation of variable wavelength coverage.
Wouldn't it be better to use an AKIMA spline rather than cubic? The galaxy templates might be well behaved, but an AKIMA spline could prevent oscillations between them which might result in a spurious fit.
ReplyDeletehttp://www.alglib.net/interpolation/spline3.php